nove.dev
:)
union-find time
+1
src/lib.rs
+1
src/lib.rs
+71
src/union_find.rs
+71
src/union_find.rs
···
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pub struct UnionFind<N> {
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nodes: Vec<Node<N>>,
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}
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impl<N> Default for UnionFind<N> {
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fn default() -> Self {
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Self { nodes: vec![] }
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}
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}
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impl<N> UnionFind<N>
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where
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N: Clone + PartialEq,
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{
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//returns a pointer to this element that can be used in union and find operations later
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pub fn make_set(&mut self, element: N) -> usize {
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let index = self.nodes.iter().enumerate().find(|(_, node)| node.inner == element);
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if let Some(index) = index {
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index.0
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} else {
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let new_node = Node {
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parent: self.nodes.len(),
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inner: element,
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};
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self.nodes.push(new_node);
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self.nodes.len() - 1
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}
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}
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/// operates on "pointers", which in this case are indexes into the internal vec
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/// but can be considered opaque to a user
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pub fn find(&mut self, element: usize) -> usize {
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let root_index = self.root_index(element);
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//take the opportunity to optimize??
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let mut x_index;
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let mut x_reference = &mut self.nodes[element];
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while x_reference.parent != root_index {
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let parent_index = x_reference.parent;
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x_reference.parent = root_index;
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x_index = parent_index;
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x_reference = &mut self.nodes[x_index];
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}
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root_index
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}
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fn root_index(&self, element_index: usize) -> usize {
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let mut root_index = element_index;
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let mut root_reference = &self.nodes[root_index];
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while root_reference.parent != root_index {
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root_index = root_reference.parent;
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root_reference = &self.nodes[root_index];
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}
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root_index
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}
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pub fn union(&mut self, elem1: usize, elem2: usize) {
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todo!()
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}
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}
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pub struct Node<N> {
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//index into the vec of nodes contained within the data structure
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//nodes are never removed or shifted within that vec
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//root nodes point to themselves
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parent: usize,
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inner: N,
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}